Researchers from the Harvard School of Public Health (SPH) have found that elevated levels of specific antibodies that fight a range of Epstein-Barr virus (EBV) antigens are associated with the onset of multiple sclerosis (MS). The study results appeared in the Dec. 26 issue of the Journal of the American Medical Association (http://www.jama.com/).
Blood samples from more than 62,000 women were collected between 1989 and 1999. The researchers documented 144 cases of MS including 18 cases with blood samples collected before the onset of the disease. For each woman with MS, two women who were the same age but did not have MS were randomly chosen as controls. Compared with their controls, the women with MS had significantly higher average blood levels of antibodies for EBV antigens before the onset of the disease. The strongest association was found for antibodies for Epstein-Barr Nuclear Antigen-2 (EBNA-2). These levels increase soon after EBV infection but normally decline within a few months. In this study, elevated levels of EBNA-2 antibodies were associated with a fourfold increase in risk of MS.
Multiple sclerosis is a chronic degenerative disease of the central nervous system. The prevalence rate in the United States is higher for individuals who live above the 37th parallel, accounting for 110-140 cases per 100,000 people, compared with 60-80 cases per 100,000 for people living below the 37th parallel. Nationwide, there are an estimated 250,000-350,000 people with MS.
Epstein-Barr virus, a member of the herpesvirus family, is one of the most common viruses in world, infecting as many as 95 percent of adults in the United States by age 40. Most people become infected at some point in their lives and show no symptoms. EBV infection during adolescence or early adulthood can cause infectious mononucleosis up to 50 percent of the time.
Lead author Alberto Ascherio, associate professor in the Departments of Epidemiology and Nutrition at the SPH, said, “For decades it has been suspected that multiple sclerosis is caused by some form of infection in genetically susceptible individuals, but the microorganisms that are responsible for it have remained elusive. Our results suggest that Epstein-Barr virus may be the culprit or, at least, one of the culprits.”
Participants for the study were chosen from the Brigham and Women’s Hospital-based Nurses’ Health Study, which began in 1976, and the Nurses’ Health Study II, which started in 1989, and has tracked the health of nurses via questionnaires and blood samples to ascertain potential risk factors for chronic disease and major medical events.
The study was supported by grants from the National Institute of Neurological Diseases and Stroke and the National Cancer Institute.